In desperation I am hoping that a reading a book about emotions might help me explain to ds1 why it is wrong to hit babies, push them over, steal toys from them etc. I try to explain but he thinks it is a hugely funny game (chanting 'don't hit baby X, it makes him sad/makes him cry etc as he whacks the baby yet again).
Needn't be a book about babies as such. Something like 'Kipper is sad when his kite blows away' would do.